Model 3 Battery Capacity

[NewTMSMan]

In an attempt to help troubleshoot a fellow Model 3 Performance owner's 100% Battery Capacity, where they are showing less than 310 miles (below 290) as the Rated Range in the main display, while my car shows 310 miles I have developed the following analysis and would like other's insight and view (note this also uses V9 Power Monitor data as well):

Here are some of the data and pictures I referenced for the calculations we discussed:


My Model 3 Performance:

Rated Range = 275 / 0.89 = 313 miles (I actually get 310 when at 100%, so this is a bit of rounding error probably).


Energy Monitor Graph:

Extrapolation yields 254 Whr/mile through measurement of the graph. This matches almost exactly with another Model 3 Performance Owner who had the patience to drive their car carefully until the Average matched the Rated line and they could just read the 254 Whr/mile. Interested in other Model 3 Performance owner's data from the Energy Monitor to see what WHr/Mile they see as the Rated number.


Model 3 EPA Data:

Based on EPA data (https://www.teslarati.com/wp-content/uploads/2017/09/Tesla-Model-3-EPA-CSI-HTSLV00.0L13.pdf):


Volts = 351V

Amps = 221.81 AHr

Power = 78.2 kWHr (Model 3 Battery Capacity based on EPA data)


Rated Whr/mile = 78200 WHr / 310 miles Rated Range =252 WHr/mile (actual rated efficiency)


So it seems all the data suggests the Rated Effectiveness for the Model 3 Performace is 252 WHr/mile and range of 310 miles with battery capacity of 78.2 KWhr available.



Model 3 RWD

This data was provided by a friend with a RWD Model 3 (please no comments about them driving their RWD harder than I drive the P ):

Extrapolation (same method I used for my Performance Model) yields 237 Whr/mile through measurement of the graph.

Using this basis and 310 miles rated range, available battery capacity would be:

Battery Capacity = 237 Whr/mile x 310 miles = 73.5 KWhr (at Rated Range and Rated WHr/mile)

So seems the RWD Model 3 has 6% lower battery capacity available compared to the Model 3 Performance based on rated data.

There are effectively 3 variables used in calculating the displayed data on the main screen for the battery capacity / range:

Battery Capacity in kWhr
Rated Range in miles
Rated Efficiency in kWHr/mile

Displayed Rated Range, miles = Battery Capacity, kWHr / Rated Efficiency, kWHr/mile

In all Model 3s the displayed Rated Range at 100% battery capacity is 310 miles. We can derive the Rated Efficiency from the Energy Monitor now displayed in V9. The only variable is the available battery capacity, which seems to be less in the RWD compared to the Performance Model.

Now I could have made errors in my above analysis or I could have information wrong so I would appreciate any review and challenge anyone can offer.

 

[JeffK]

Displayed range is not necessarily the range you'll get. They all have the same battery capacity as far as we know.

I'm averaging 320 Wh / mi in my Performance version, btw.

 

[NewTMSMan]

Displayed range is not necessarily the range you'll get. They all have the same battery capacity as far as we know.

I'm averaging 320 Wh / mi in my Performance version, btw.

Yes I know that, it's not the point. The point is the available battery capacity seems different on the RWD vs. the Performance Model 3. They may have the same battery, but it seems they do not have the same available capacity. what I really need is confirmation of the Rated Energy Efficiency in the V9 Energy Monitor and also the 100% Battery Capacity Rated Range displayed.

 

[ewoodrick]

In an attempt to help troubleshoot a fellow Model 3 Performance owner's 100% Battery Capacity, where they are showing less than 310 miles (below 290) as the Rated Range in the main display, while my car shows 310 miles I have developed the following analysis and would like other's insight and view (note this also uses V9 Power Monitor data as well):



Extrapolation yields 254 Whr/mile through measurement of the graph. This matches almost exactly with another Model 3 Performance Owner who had the patience to drive their car carefully until the Average matched the Rated line and they could just read the 254 Whr/mile. Interested in other Model 3 Performance owner's data from the Energy Monitor to see what WHr/Mile they see as the Rated number.


Model 3 EPA Data:




So it seems all the data suggests the Rated Effectiveness for the Model 3 Performace is 252 WHr/mile and range of 310 miles with battery capacity of 78.2 KWhr available.




So seems the RWD Model 3 has 6% lower battery capacity available compared to the Model 3 Performance based on rated data.

There are effectively 3 variables used in calculating the displayed data on the main screen for the battery capacity / range:

Battery Capacity in kWhr
Rated Range in miles
Rated Efficiency in kWHr/mile


In all Model 3s the displayed Rated Range at 100% battery capacity is 310 miles. We can derive the Rated Efficiency from the Energy Monitor now displayed in V9. The only variable is the available battery capacity, which seems to be less in the RWD compared to the Performance Model.

Now I could have made errors in my above analysis or I could have information wrong so I would appreciate any review and challenge anyone can offer.

No, I believe that you are missing that the EPA figures aren't necessarily the right numbers. In a post yesterday, someone gave a really detailed overview of all of the performance numbers. Some of the possibly more enlightening info is that EPA numbers are a joint agreement between EPA and Manufacture, not necessarily representing reality. And that the 3 different versions of the Model 3 do indeed have different efficiency numbers.

 

[JeffK]

The point is the available battery capacity seems different on the RWD vs. the Performance Model 3.

They aren't different though and you're ignoring the fact that Tesla requested the rated range to be lower on the RWD model.

 

[TJKR]

You can't really calculate your car's battery capacity this way and absolute battery capacity varies from car to car.

From what we know, all LR versions of the Model has 4,416 - '2170' cells. The cells have a nominal voltage of 3.7V and designed capacity of 5.75 amp hours. 3.7 x 5.75 x 4,416 = 93,950.4 designed watt hours or 93.95 Kwh. However not all 2170 cells are the same and they individually have their own 'personalities'. Some may actually be 5.76 amp hours, some 5.81 amp hours, some 5.69.. etc. Also each cell charges and discharges at different rates and this may vary further depending on how they are stressed and temperature. That is where the BMS comes in to balance the cells to try and make them behave the same way. To account for this, there are some safetys built in not to over charge or under charge the batteries and also limit discharge and charge rates. From what I understand, Tesla has set a upper and lower charge limit to preserve the battery life. So in theory you are only using about 80% of the battery, thus the 75 kwh or so battery capacity.

Conclusion... not all batteries will be exactly the same size and your battery capacity will degrade over time on your charging behavior (what charging limit you set and how much you use it and how fast you charge it (generally slower the better), discharging stress, how many times are you flooring the car and how often, and ambient temperature.

So the more you floor the car, the more you drive it in extreme environments, the more you charge and discharge the battery from 0-100% and more you supercharge, the faster your battery will degrade.

 

[NewTMSMan]

No, I believe that you are missing that the EPA figures aren't necessarily the right numbers. In a post yesterday, someone gave a really detailed overview of all of the performance numbers. Some of the possibly more enlightening info is that EPA numbers are a joint agreement between EPA and Manufacture, not necessarily representing reality. And that the 3 different versions of the Model 3 do indeed have different efficiency numbers.

Yes I understand that, the agreed number with the EPA is the 310 Mile Rated Range for all Model 3s. To get that to display there are only 2 options; have all the Rated Efficiencies (not actual, but Rated) be the same, or if the Rated Efficiencies are different (as I have shown they are) , have the Available Battery Capacity be different to offset the difference in Rated Efficiency. There really is no other option that I can think of.

They aren't different though and you're ignoring the fact that Tesla requested the rated range to be lower on the RWD model.

No the Rated Efficiencies are different, please see the 2 graphics I provided for the Performance and RWD Model 3s from V9 Energy Monitor. They are different in those charts. If they are different and the Rated Range is the same (310 Miles in all Model 3s), the only way to make the math work to get 310 miles @ 100% battery charge is to change the available battery capacity in each model. I am not saying the batteries are different, but I am saying this seems to point out that the RWD has the available battery capacity limited. If you can provide a reference that shows any kind of measurement or analytics showing the available battery capacities are the same, can you share a link?

 

[JeffK]

please see the 2 graphics I provided

None of the images work for me. Looks like links to your email...

 

[NewTMSMan]

You can't really calculate your car's battery capacity this way and absolute battery capacity varies from car to car.

From what we know, all LR versions of the Model has 4,416 - '2170' cells. The cells have a nominal voltage of 3.7V and designed capacity of 5.75 amp hours. 3.7 x 5.75 x 4,416 = 93,950.4 designed watt hours or 93.95 Kwh. However not all 2170 cells are the same and they individually have their own 'personalities'. Some may actually be 5.76 amp hours, some 5.81 amp hours, some 5.69.. etc. Also each cell charges and discharges at different rates and this may vary further depending on how they are stressed and temperature. That is where the BMS comes in to balance the cells to try and make them behave the same way. To account for this, there are some safetys built in not to over charge or under charge the batteries and also limit discharge and charge rates. From what I understand, Tesla has set a upper and lower charge limit to preserve the battery life. So in theory you are only using about 80% of the battery, thus the 75 kwh or so battery capacity.

Conclusion... not all batteries will be exactly the same size and your battery capacity will degrade over time on your charging behavior (what charging limit you set and how much you use it and how fast you charge it (generally slower the better), discharging stress, how many times are you flooring the car and how often, and ambient temperature.

So the more you floor the car, the more you drive it in extreme environments, the more you charge and discharge the battery from 0-100% and more you supercharge, the faster your battery will degrade.

I am not calculating Actual Battery Capacity, I am calculating Rated Battery Capacity, or what I am calling Available Battery Capacity and using all Rated Numbers, not any actual numbers.

I think we can agree:

Rated Range, miles = Rated Battery Capacity, kWh / Rated Efficiency, Whr/mile x 1000 or
Rated Battery Capacity, kWh = Rated Efficiency, Whr/mile x Rated Range, miles / 1000

We know the following:
Rated Range for all Model 3 Cars = 310 Miles
Rated Efficiency Model 3 Performance = 252 Whr/mile (derived from Energy Monitor Graph for Rated as provided by Tesla in V9)
Rated Efficiency Model 3 RWD = 237 Whr/mile (derived from Energy Monitor Graph for Rated as provided by Tesla in V9)

Therefore the only answer for Rated Battery Capacities are:

Model 3 Performance Rated Battery Capacity = 310 x 252 / 1000 = 78.1 kWhr
Model 3 Performance Rated Battery Capacity = 310 x 237 / 1000 = 73.5 kWhr

Therefore;

% Difference of Rated Battery Capacity = (78.1 - 73.5) / 78.1 = 6%

All the numbers I used are the Rated numbers I derived from Tesla provided data, I am not using any car specific data.

 

[JeffK]

 

[NewTMSMan]

None of the images work for me. Looks like links to your email...

Sorry for that. Please see images below (hopefully):

Model 3 Performance Energy Monitor Graph (showing Rated Efficiency):

Model 3 RWD Energy Monitor Graph (showing Rated Efficiency):

 

[NewTMSMan]

Can see the Can Bus reports the nominal battery capacity of 77.5 kWHr, which is close to the EPA number I derived. Not sure if there are other settings not shown that could limit the access to the full battery, or possibly they just introduce a factor in the Rated calculations to arrive at 310 miles, but then why not just have the Rated Efficiency just be the same for all Model 3s?

 

[JeffK]

Can see the Can Bus reports the nominal battery capacity of 77.5 kWHr, which is close to the EPA number I derived. Not sure if there are other settings not shown that could limit the access to the full battery, or possibly they just introduce a factor in the Rated calculations to arrive at 310 miles, but then why not just have the Rated Efficiency just be the same for all Model 3s?

...because it's not the same. Performance model and AWD have a lower true range than RWD regardless of what the number says.

 

[NewTMSMan]

...because it's not the same. Performance model and AWD have a lower true range than RWD regardless of what the number says.

Again, I am not talking about true or actual range or battery capacity in any of my posts, comments or calculations. Everything is Rated as provided by Tesla data.

 

[JeffK]

So the entire post is just talking about the estimated numbers in V9 and nothing to do with actual numbers or actual range or anything real but merely attempting to dervive V9's estimate formula?

 

[NewTMSMan]

So the entire post is just talking about the estimated numbers in V9 and nothing to do with actual numbers or actual range or anything real but merely attempting to dervive V9's estimate formula?

I am going to go out on a limb here and guess you are not an engineer....

The post points to the available battery capacity being different in different Model 3 models based on the Rated Efficiency and Rated Range for the Model 3. I honestly don't know how I can be more clear about that, I have simplified the math and the concepts to make it as easy to understand as I can at this point. If it's not landing for you, that's OK.

 

[JeffK]

The post points to the available battery capacity being different in different Model 3 models

Getting 75 kWh on RWD

 

[suttonlr]

My question would be how do you explain the reports of RWD owners getting 350-375 actual driven miles on their odometer?

How about you and your AWD buddy just start driving and see who runs out of juice first?

 

[animorph]

I haven't looked at the at the new Energy Graph for the Model 3, but from the pictures I'm not seeing a rated efficiency number, only an average which is from the last few miles of driving. There is a constant used for rated miles, different for each car. I'm not sure you are using the right numbers.

The Model 3 RWD rated range was reduced voluntarily by Tesla so that the AWD cars, which are less efficient, would have roughly the same rated range. Given the the battery is the same for all, the RWD is more efficient, and Tesla claims all version have 310 miles rated range, yes, the calculated battery sizes would be larger for AWD than RWD. In reality, the RWD will be able to travel farther than the AWD, maybe even by the 6% you calculated.

TL;DR, the 310 mile range is an inaccurate made-up number that should not be used to calculate battery size.

 

[NewTMSMan]

Getting 75 kWh on RWD

Only 66 kWHr with 110 WHr/mile and 606 miles.

That is why I am not using their displayed actual usage data and am using their provided Rated data only.

Now the issue with my calculations may be that the Rated Efficiency is not being displayed properly in the Energy Monitor but, I have additional data from Remote S App (cannot share publicly as it is not for my cars) that shows RWD with 72 kWh battery capacity compared to it showing 75 kWhr capacity for my P. Now I only have that data for 1 car and that individual car may have battery issues so would not rely on this.

The calculations I provided are simple and based on Telsa data. Where in the calculations or the data I am using is there an issue that would point to me being wrong here?